1. Field of the Invention
The present invention relates to a control element for a motor vehicle, particularly a rotary actuator, including at least one pivoted control knob, an extension formed on the control knob, and an electrical means to detect the rotary movement of the control knob, whereby the electric means works together with the control knob extension.
2. Description of the Background Art
Highly different systems are prior in the art to detect rotary movements at a rotary actuator in a motor vehicle. Thus, German Unexamined Pat. Application No. DE 103 04 804 A1 describes an electric switch, especially a joystick type switch or cursor type switch, which is also provided with means to detect a rotation of an operating element of the electric switch. On the pivoted operating element an extension is integrally formed at whose end tooth elements are formed in the shape of castle battlements. The tooth elements in this case act together with two light barriers, whose light is interrupted by the tooth elements during rotation of the operating element so that the movement is detectable. The two light barriers are arranged in such a way that the particular rotational direction of the operating element is detectable. It can be derived from the description that other sensory operating switching elements such as Hall sensors may also be used.
The use of Hall sensors to detect motion in a switch is described in German Utility Model No. DE 94 15 257 U1. A ferromagnetic object, located centrally above two Hall generators, is affixed on a lock cylinder. If rotation now occurs at the lock cylinder, then a tripping portion is moved to an off-center position relative to a Hall difference IC. In this position, a difference in the magnetic flux between the two Hall generators is perceived. Depending on whether the tripping portion is off-center to the left or right, the difference in the magnetic flux is positive or negative. Therefore, the use of Hall generators in combination with a ferromagnetic object and a permanent magnet is described.
German Utility Model No. DE 20 2005 019 271 U1 describes the use of Hall sensor elements to detect movement in a multi-stage contactless switch, particularly for a control element in a motor vehicle. A two-pole permanent magnet is disposed rotated around its central axis to a sensor axis on which the Hall sensors are attached. By means of a movement of the permanent magnet in relation to the sensor axis, the magnetic field detectable by the Hall sensors changes, so that a switching process is detectable.